Research Fellows Directory
Dr Jason Robinson
University of Cambridge
I direct research in the fields of superconductivity and spintronics with a focus on investigating the electronic coupling between materials that display radically different properties such as magnetism and superconductivity. The interaction of superconducting and magnetic phases at superconductor-ferromagnet interfaces has captured the imagination of physicists even before Bardeen, Cooper and Schrieffer formulated the fundamental theory of superconductivity in 1957. Superconductivity and ferromagnetism are incompatible, as superconductivity results from the pairing of electrons with antiparallel spins (singlet pairs), while ferromagnetism requires a parallel alignment of electron spins. Consequently, singlet pairs are destroyed within nanometers of entering a ferromagnet from a superconductor. However, in one of my first major publications -“Controlled injection of spin-triplet supercurrents into a strong ferromagnet” (Science 2010)- we demonstrated that by coupling a superconductor to a magnetically inhomogeneous ferromagnet, the singlet pairs could transform into triplet pairs, which have parallel spins, so as to make the superconductivity compatible with ferromagnetism.
Whilst triggering the new field of superconducting spintronics, the discovery of spin-polarized electron pairs is inspiring the development of cryogenic computing as a low energy alternative to semiconductor-transistor logic, as described in my review in Nature Physics (2015). Non-superconducting spintronics is already seen as a competitor technology as data processing based on the spin of an electron can be faster than the charge-based equivalent in semiconductor-based logic. However, generating the necessary spin currents is not low-power as large charge currents are required at device inputs. Superconducting spintronics offers a real breakthrough in this context as spin-currents are generated in the absence of dissipation.